[Malignant thymoma with intracranial metastases]

Malignant thymomas usually proliferate invasively and rarely metastasize to other organs. Since the metastases occur predominantly to the liver and kidneys, there have been only 16 cases with metastatic spreads of malignant thymomas to the central nervous system reported in the literature. A 59-year-old man was admitted with complaints of dizziness and vomiting. Three years and three months ago, he had been operated upon for mediastinal tumor, which was diagnosed as a predominantly lymphocytic type thymoma, and then followed by irradiation therapy of 3800 rads. The size of the tumor decreased markedly after the irradiation. Nine months after the operation, he complained again of dizziness and vomiting. Computed tomography scans showed a tumorous lesion in the right cerebellar hemisphere, which was thought to be a metastasis from the thymoma. He received radiotherapy of 4000 rads directed to the intracranial metastatic tumor, with the reduction of the tumor size and the relief of symptoms. On the present admission, he had cerebellar signs and symptoms. Neuroradiologically, there was a hypervascular tumor in the left cerebellar hemisphere and a hypovascular one in the right. At operation, a vascular and solid tumor with small necrotic areas were found in the left cerebellum, and a tumor with large liquefied clot within it in the right cerebellum. Pathologically, bilateral cerebellar tumors were confirmed as the metastases from the thymoma in the epithelial type.